Astroblog

Obscured by Clouds. The rough and ready blog of a cloud benighted biologist and amateur astronomer. Astroblog will cover my interests in astronomy, biology and Life, the Universe and Everything.

Wednesday, August 31, 2011

Comet Elenin in STEREO H1B (August 25 and 26)

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 25. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines and weird loopy bits are imaging artifacts.

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 26. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines and weird loopy bits are imaging artifacts.

I've plotted the intensity of comet Elenin images relative to a reference star (indicated on the image from the 26th) from the 18th to the 26th. I have the data from the 27th, but the comet passes over a bright star and I can't separate out the brightness of the comet from the star.

There is some dropped points on the 23rd when the imaging arefact of Mercury passed over the comet and reference star images. Again, click to embiggen.

As I've stated before, on calibrated images the comet has faded over 80% since the 19th, however, using this method of normalising (compared to how I did it on the calibrated images earlier) the drop is more like 70%.

Again, we have to factor in that it is further away from the H1B camera despite being closer to the Sun. I have not explicitly tried to calculate magnitudes, especially since Elenin is an extended source.

Anyway, important things to notice: The Coronal Mass Ejection that did all the fancy tail twirling hit between two flare-ups of the comet. The second peak (coming after the arrow showing where the peak CME hit, comes after the CME has washed over it (ie the big peak is not an artefact of the CME brightness adding to the comet, it genuinely gets brighter). The next peak is an aretfact form the comet crossing in from of a star, but the peak after that, although it crosses a star early, is probably also a flare.

Images from STEREO on the 27th (image right) don't show the same nucleus elongation that you see in Michaels images on the 27th, but with the STEREO images it's like looking through a pair of 7x30 binoculars compared to the telescopic images. I don't expect to see much until later images.

Tuesday, August 30, 2011

The Sky This Week -September 1 to Thursday September 8

The First Quarter Moon is Monday September 5. Jupiter is high in the morning sky. Mars and Mercury are visible in the morning sky. Saturn is low in the western evening sky and visited by the Moon September 1. Comet C/2009 P1 Garrad is visible in binoculars in the northern sky.

Morning sky looking north-east as seen from Adelaide at 6:00 am local time on Sunday September 4 showing Mars, Mercury and the brighter stars. Similar views will be seen elsewhere at the equivalent local time. Click to embiggen.

The First Quarter Moon is Monday September 5.

In the morning Jupiter is high above the northern sky. Now is a good time to begin telescopic observation of this massive world, or follow its moons in binoculars.

Mars is low in the eastern sky, in the constellation of Gemini. Mars starts the week not far from the relatively bright star Wasat.

Mercury is quite close to the horizon in the morning skies. Mercury comes close to the bright star Regulus during the week, although you will need a clear level horizon to see it.

Evening sky on Thursday September 1 looking west as seen from Adelaide at 7:30 pm local time in South Australia showing Saturn in the early evening sky not far form the crescent Moon. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

Saturn is readily visible as the bright yellowish object not far from the bright star Spica. It is now too low in the sky for successful telescopic observation.

Saturn is not far from the crescent Moon on Thursday September 1, the Moon will be very close to the bright star Spica at this time.

The location of Vesta as seen at 9:00 pm on Saturday September 3 looking north-east from Adelaide, similar views will be seen at equivalent local times elsewhere. Click to embiggen,

The asteroid Vesta is now past opposition, but is still readily visible in binoculars and is just atthe threshold of unaided eye visibility (magnitude 6). To see it with the unaided eye you will need to be in a dark sky location though.

Vesta starts the week very close to the relatively bright star Phi Capricorni, making it very easy to find. During the week it moves away from Phi Capricorni.

Vesta moves significantly night to night, so will be easy to follow. A chart showing Vesta's location is here.

The location of Comet C/2009 Garrad as seen at 9:30 pm Saturday September 3 looking north from Adelaide, similar views will be seen at equivalent local times elsewhere. Click to embiggen,

Comet C/2009 Garrad is visible in binoculars in the northern sky, in the constellation of Sagitta, the Arrow.

Although it has brightened substantially, it is still only a fuzzy dot at magnitude 7. The best views will be under dark skies, where you might spy a short faint tail. The best viewing is around 10:00 pm, when the comet is almost due north and highest in the sky. During the week the comet will be in binocular range of a number of clusters, including Brocchi's cluster .

Comet Elenin in STEREO H1B (August 23 and 24)

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 23. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines are imaging artifacts.

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 24. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines and weird white blobs are imaging artifacts.

Once again, as with this post and this post I've zoomed and cropped these images of Comet Elenin from the STEREO H1B imager in order to capture the tail of Elenin. It doesn't really work so well this time as the comet is fading rapidly. On calibrated images the comet has faded over 80% since the 19th, but we have to factor in that it is further away from the H1B camera despite being closer to the Sun. Mercury is in the field of view, and an asteroid on the 23rd (there is lots more on the larger images). Here's the AVI animation of the August 23 images (1 Mb) and the AVI animation of the August 24 images (1 Mb).

Carnival of Space #212 is here.

Carnival of Space #212 is now up at the Next Big Future. There the search for rocky exoplanets, how far can earth rocks travel, finding sunspots as they form and much, much more. head on over for a look.

Comet Elenin in STEREO H1B (August 21 and 22)

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 21. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines are imaging artifacts.

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 22. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines are imaging artifacts.

As with the previous post I've zoomed and cropped these images of Comet Elenin from the STEREO H1B imager in order to capture the tail of Elenin. Presenting the images this way makes the tail easier to see. On the 21st another solar flare passed over Elenin, but the effects weren't so dramatic this time. Elenin does seem to be fading more, but I need to calibrate the images to be sure. Mercury is now in the field of view, and an asteroid on the 21st (there is lots more on the larger images, an the 23rd has a couple more coming through). Here's the AVI animation of the August 21 images (1 Mb) and the AVI animation of the August 22 images (1 Mb).

Friday, August 26, 2011

Comet Elenin Fades

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 19. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines are imaging artifacts.

Well, in the wake of that event the brightness of comet Elenin has dropped dramatically, by almost a magnitude (from magnitude 8.1 on the 19th to magnitude 8.9 on the 23rd, the last reported magnitude). You can see before and after images by Rob Kaufmann here showing the drop. Michael Mattiazzo also has images of comet Elenin before and after the flare with estimates of the comet magnitude here.

So what is happening? What is most likely going is that the bast of energetic solar wind particles has eroded exposed "ices" (water and carbon dioxide) creating the brief highly active tail (comet Elein has had a small but nice tail for some time). With these exposed ices gone, the generation of dust and gas drops off and the magnitude drops. UPDATE: Jakub Cerny thinks it is more likely due to depletion of particles in the inner coma, causing dimming that way. Also see Michael Mattiazzo's latest images here, showing what looks to be an elongated nucleus.

Elenin is a new comet, this is the first time it has dropped in to the inner solar system from the Oort Cloud. New comets generally are bright early than drop off quickly as their surface ices are depleted. Older comets tend to be brighter due to fissures and cracks penetrating more deeply into the comet allowing more volatiles to be accessed.

What does it mean for the future? Comets, despite the images of them that look like asteroids, and quite fragile, loose agglomerations of dust and ices smeared together. It has already been suggested that Elenein will not survive perihelion. This recent dimming of Elenin suggests it may be sufficiently fragile to evaporate as it passes close to the Sun, astronomers will be watching this small but cute comet as it plunges towards perihelion for more clues about the structure and dynamics of comets.

Walking to Work This Morning

Wednesday, August 24, 2011

The Sky This Week - Thursday August 25 to Thursday September 1

The New Moon is Monday August 29. Jupiter is high in the morning sky. Mars is visited by the thin crescent Moon on the 25th. Mercury enters the morning sky and is close to the thin crescent Moon on August 28. Saturn is low in the western evening sky and visited by the Moon August 31. Comet C/2009 P1 Garrad is visible in binoculars in the northern sky.

Morning sky looking north-east as seen from Adelaide at 6:00 am local time on Thursday August 25 showing the Moon, Mars, Mercury and the constellations. Similar views will be seen elsewhere at the equivalent local time. Click to embiggen.

Mars is low in the eastern sky, in the constellation of Gemini. Mars starts the week not far from the relatively bright star Mebsuta (eta Geminorium) and heads towards the star Wasat. On the 25th Mars is close to the thin Crescent Moon.

Mercury enters the morning skies, but is still quite close to the horizon, on Sunday August 28 the thin crescent Moon is close to Mercury, although you will need a clear level horizon to see it.

Evening sky on Wednesday August31 looking west as seen from Adelaide at 7:00 pm local time in South Australia showing Saturn in the early evening sky not far form the crescent Moon. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

Saturn is readily visible as the bright yellowish object not far from the bright star Spica. It is getting lower in the sky, and the window for telescopic observation is narrower.

In this short timespan, even in small telescopes you can see Saturn's rings and it's moon Titan. Despite being past opposition, when Saturn was at its biggest, Saturn is still big and beautiful.

The location of Vesta as seen at 8:00 pm on August 27 looking east from Adelaide, similar views will be seen at equivalent local times elsewhere. Click to embiggen,

The asteroid Vesta is now past opposition, but is still readily visible in binoculars and is just over the threshold of unaided eye visibility (magnitude 5.9). To see it with the unaided eye you will need to be in a dark sky location though.

Vesta starts the week close to the relatively bright star Phi Capricornii, making it very easy to find. During the week it gets even closer to Phi Capricorni.

Vesta moves significantly night to night, so will be easy to follow. A chart showing Vesta's location is here.

The location of Comet C/2009 Garrad as seen at 9:00 pm Saturday August 27 looking north from Adelaide, similar views will be seen at equivalent local times elsewhere. Click to embiggen,

Comet C/2009 Garrad is visible in binoculars in the northern sky, in the constellation of Sagitta, the Arrow.

Although it has brightened substantially, it is still only a fuzzy dot at magnitude 7. The best views will be under dark skies, where you might spy a short faint tail. The best viewing is around 10:30 pm, when the comet is almost due north and highest in the sky. During the week the comet will be in binocular range of a number of clusters, including M71.

Tuesday, August 23, 2011

Comet Elenin in STEREO H1B (August 19 and 20)

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 19. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines are imaging artifacts.

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 20. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines are imaging artifacts.

I've done something different here. I've zoomed and cropped these images of Comet Elenin from the STEREO H1B imager in order to capture the tail of Elenin. Presenting the images this way makes the tail easier to see. On the 19th a solar flare passed over Elenin and the tail flared as well and was twisted about. The weird white patches in the image of the 19th are artefacts of the background subtraction process I use. It looks better in animation. Here's the AVI animation of the August 19 images (1 Mb) and the AVI animation of the August 20 images (1 Mb).

Monday, August 22, 2011

Comet Elenin in STEREO H1B (August 16 and 17)

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 16. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Bright lines are imaging artifacts.

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 17. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Bright lines are imaging artifacts.

Comet Elenin is passing across the STEREO H1B field of view fading as it goes. The comet is actually brighter on the 16th than the 17th, despite what it looks like in the image, as the corona was much brighter on the 16th, and washed out the comet when I increased the brightness. I've made a little AVI animation of the August 17 images (1 Mb).

Thursday, August 18, 2011

Homeopaths try and Silence Blogger

The Italian arm of multinational homoeopathic medicine company Boiron is threatening to sue an amateur blogger (BlogZero) over posts he has made that were critical of homoeopathy. If the company was expecting to muffle criticism, boy, did they get that wrong, the story has exploded over the intertubes.

Carnival of Space #210 is here.

Carnival of Space #210 is now up at Dear Astronomer (well, it's been up for two days, but I've been distracted). There's liquid water on Mars, comet 45 Honda etc. etc., the rebirth of SETI, fusion propulsion and much, much more. Hop on over and have a read.

Simulation of the view from STEREO B on August 17 using Celestia (slightly inaccurate due to old orbital elements)

On August 14 Comet Elenin entered the STEREO H1B field of view without the satellite having to be rolled (tip of the hat to Comet Al for alerting me). Over the next few days we should have some excellent views of the comet, which is quite bright, but not spectacular, in the H1B imager. I've made a little AVI animation of it (2 Mb). A far better animation of the comet from 6 August to 12 August (when the spacecraft rolled) is here (warning 24 Mb animation).

We've been waiting for this ever since Elenin came into range of the H2B wide field imager (see here for animation). We also got some nice images from H1B when the STEREO spacecraft was rolled to position from August 6 (see here (scroll down for animations) and here for images). But now we can see the comet without rolling the spacecraft, which will allow for more consistent imaging.

Location of comet C/2010 X1 Elenin at 8:00 pm ACST as seen from Adelaide. Similar views will be seen in Australia elsewhere at the equivalent time.

If you live in the southern hemisphere, you can see the comet yourself. It is quite low to the horizon at astronomical twilight (1.5 hours after sunset), when it is dark enough to see the comet. Using a telescope can be tricky that low.

The comet is roughly magnitude 9, still to dim for standard binoculars, so currently you do need a modest telescope to see it. However it will brighten over the week and be visible in binoculars by August 27.

Map suitable for locating Elenin in binoculars (click to embiggen).

Use the colour chart above to orient yourself and locate Saturn, then use the binocular map, the circle is the approximate field of view of 10x50 binoculars. You can get orbital elements here.

The Sky This Week - Thursday August 18 to Thursday August 25

Last Quarter Moon is Monday August 22. Jupiter is high in the morning sky and visted by the Moon on the 19th and 20th. Mars is close to stars in Gemini, and visited by the thin crescent Moon on the 25th. Saturn is low in the western evening sky. Comet C/2009 P1 Garrad is visible in binoculars in the northern sky.

Morning sky looking north-east as seen from Adelaide at 6:00 am local time on Saturday August 20 showing the Moon, Jupiter, Mars and the constellations. Mars is close to the star Mebsuta. Similar views will be seen elsewhere at the equivalent local time. Click to embiggen.

The Last Quarter Moon is Monday August 22.

In the morning Jupiter is high above the north-eastern sky. It is visted by the waning Moon on the 19th and 20th.

Mars is low in the eastern sky, in the constellation of Gemini. Mars stars the week close to the relatively bright star Mebsuta (eta Geminorium). On the 25th Mars is close to the thin Crescent Moon.

Bright white Venus and swift Mercury are now lost in the twilight glow.

Evening sky on Saturday August 20 looking west as seen from Adelaide at 8:00 pm local time in South Australia showing Saturn in the early evening sky. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

Saturn is readily visible as the bright yellowish object not far from the bright star Spica. It is getting lower in the sky, and the window for telescopic observation is narrower.

In this short timespan, even in small telescopes you can see Saturn's rings and it's moon Titan. Despite being past opposition, when Saturn was at its biggest, Saturn is still big and beautiful.

The location of Vesta as seen at 8:00 pm on August 20 looking east from Adelaide, similar views will be seen at equivalent local times elsewhere. Click to embiggen,

The asteroid Vesta is now past opposition, but is still readily visible in binoculars and is just over the threshold of unaided eye visibility (magnitude 5.9). To see it with the unaided eye you will need to be in a dark sky location though.

Vesta starts the week between the relatively bright stars 24 Capricorni and Phi Capricornii, making it very easy to find. 24 Capricorni is the fifth star up and to the right of the brightest star in Capricornus (see image to left). During the week it gets even closer to Phi Capricorni.

Vesta moves significantly night to night, so will be easy to follow. A chart showing Vesta's location is here.

The location of Comet C/2009 Garrad as seen at 9:00 pm Saturday August 21 looking north from Adelaide, similar views will be seen at equivalent local times elsewhere. Click to embiggen,

Comet C/2009 Garrad is visible in binoculars in the northern sky, initially in the constellation of Delphinus, the Dolphin, then moving to Sagitta, the Arrow.

Although it has brightened substantially, it is still only a fuzzy dot at magnitude 7. The best views will be under dark skies, where you might spy a short faint tail. The best viewing is around 11 pm, when the comet is almost due north and highest in the sky. By the end of the week the comet will be in binocular range of a number of cluates, including M71.

The stickers you are looking for. This is for the Deodicurus at the corner of North Terrace and Frome Road. I never did find the Rundle Mall ones.

The Jurassic Week site also has a map that locates the dinosaurs. However, zoomed out it is quite inaccurate. You have to zoom in to get an accurate location (best in satellite mode, although slower, you can get landmarks that way as well). For example, at standard zoom it looks as if the dinosaurs near the SA museum are behind the museum, when they are in front on the North Terrace side.

Each dinosaur viewing area is marked with a sticker (see left), but even though the stickers are big, they can be difficult to spot. Some patience is required.

The LAYAR software generates an image that lets you walk around the animal and take pictures from different angles and distances (see above). You can submit your pictures to yourpics@adelaidenow.com.au.

The LAYAR app has a little radar screen that tells you how far away you are and in what direction from the dinosaur. However, I found on my phone (Sony-Ericsson Xperia mini-Pro, running Android) the dinosaurs were very unstable, even when nearly on top of a dinosaur that you have been following, the signal will suddenly drop and "no dinosaurs found" come up. Even if you are in the middle of photographing a dinosaur, it can drop out (and the image can shift around a lot while you are trying to photograph it). For the Ceratosaurus at the balls, I had to walk some distance past it before it registered and then I walks back to it.

It's not just me, I ran into another dinosaur hunter with an iPod who was having the same problems (amusingly, we were imaging the same dinosaur, but the software said it was in a different direction for both of us). Still, if you go slowly and have patience catching the dinosaurs is great fun.

So if you see someone peering intently into space, holding up a mobile phone as they shuffle around in different directions, chances are its a dinosaur hunter.

Saturday, August 13, 2011

Unexpected Mobile Rainbows (part 3)

Comet 45P Honda-Mrkos-Pajdusakova visible in the Southern Skies

Left image; location of comet 45P in the southern sky at 10:00 pm and right image, location of 45P in the southern skies at 5:00 am (click on images to embiggen into printable charts).

Comet Comet 45P Honda-Mrkos-Pajdusakova is now bright enough to see in binoculars in the Southern Hemisphere skies. Unfortunately, it is also a time when the bright Full/almost Full moon is in the skies. It is best seen early in the morning, when the comet is at its highest, and the Moon is low on the horizon. Tonight (Saturday 13 August), it is close to lots of beautiful clusters in the Small Magellanic Cloud.

Unfortunately for Stellarium users, Stellarium gives the wrong position for 45P.

Map suitable for use with binoculars, to locate the comet tonight. The rectangle is the approximate field of view of GRAS-12, the circle is the approximate field of view of 10x50 binoculars. UPDATE: clouded out

Unexpected Mobile Rainbows (part 3)

Thursday, August 11, 2011

Carnival of Space #209 is here.

Carnival of Space #209 is now up at Starry Critters. This one is rather special, so pop over and have a look. There's the phantom planets of Barnards' Star, anti-protons in space, solar seaweed and much more. Zip over and click on through.

Tuesday, August 09, 2011

The Sky This Week - Thursday August 11 to Thursday August 18

The Full Moon is Sunday August 14. Jupiter is high in the morning sky. Mars close to stars in Gemini. Saturn is low in the western evening sky. Comet C/2009 P1 Garrad is visible in binoculars in the northern sky.

Morning sky looking north-east as seen from Adelaide at 6:00 am local time on Saturday August 13 showing the Mars and the constellations. Mars is close to the open cluster M35. Similar views will be seen elsewhere at the equivalent local time. Click to embiggen.

The Full Moon is Sunday August 14.

In the morning Jupiter is high above the north-eastern sky. Mars is low in the eastern sky, in the constellation of Gemini. Mars forms and attractive triangle with some of the moderately bright stars (Propus and Tejat). By the end of the week it is close to Mebsuta (eta Geminorium).

Bright white Venus and swift Mercury are now lost in the twilight glow.

Evening sky on Saturday August 13 looking west as seen from Adelaide at 8:00 pm local time in South Australia showing the Moon, and Saturn in the early evening sky. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

Mercury is lost in the twilight glow.

Saturn is readily visible as the bright yellowish object not far from the bright star Spica. It is getting lower in the sky, and the window for telescopic observation is narrower.

In this short timespan, even in small telescopes you can see Saturn's rings and it's moon Titan. Despite being past opposition, when Saturn was at its biggest, Saturn is still big and beautiful.

The location of Vesta as seen at 9:00 pm on August 13 looking east from Adelaide, similar views will be seen at equivalent local times elsewhere. Click to embiggen,

The asteroid Vesta is becoming brighter and is now readily visible in binoculars and is just over the threshold of unaided eye visibility (magnitude 5.7). To see it with the unaided eye you will need to be in a dark sky location though.

Vesta starts the week close to the relatively bright star 24 Capricorni, making it very easy to find. 24 Capricorni is the fifth star up and to the right of the brightest star in Capricornus (see image to left). It then heads further up the sky towards another relatively bright star Phi Capricorni.

Mid-week bright moonlight will interfere with your ability to see Vesta, although it should remain visible in good binoculars.

Vesta moves significantly night to night, so will be easy to follow. A chart showing Vesta's location is here.

The location of Comet C/2009 Garrad as seen at 9:00 pm August 14 looking north from Adelaide, similar views will be seen at equivalent local times elsewhere. Click to embiggen,

Comet C/2009 Garrad is now visible in binoculars in the northern sky, in the constellation of Delphinus, the Dolphin. It is only a fuzzy dot, and will be hard to locate under suburban skies. So if you have dark skies it is well worth watching. However, mid-week bright moonlight will make it difficult to see the comet.